Then he slipped into the bedroom that March 30 afternoon for some alone time with his girlfriend, Lauren Roe, according to the Pasco County Sheriff's Office. While Michalski tried to get his girlfriend to have sex with him, he could hear the boys — ages 2 and 1 — turning on the water at least twice, authorities said.

He yelled at them to stop.

When he checked on the boys a few minutes later, the sheriff's report said, he found 1-year-old Dyllan "face up and unresponsive." Paramedics swarmed to the scene, but it was too late to save him.

Dyllan, who had just celebrated his first birthday, was taken off life support and died the next day. An autopsy determined the cause of death was drowning.

It took months for authorities to investigate and confer with the Pasco-Pinellas State Attorney's Office to determine whether someone would face charges in the case.

On Wednesday, Dyllan's father was charged with aggravated manslaughter of a child and child neglect. Michalski, 22, of 7801 Fox Hollow Drive, is being held without bail at the Land O'Lakes jail.

"Sometimes, it takes a while to ensure that the case is ready to move forward with all the evidence and information we have," said sheriff's spokesman Kevin Doll.

Roe's mother, Theresa Griffiths, 41, said Wednesday that Michalski made a mistake when he left the boys alone in the bathtub on that spring afternoon.

"I go to bed dreaming of my grandson as he drowns, and I can't reach him," she said.

Griffiths urged other parents to learn from the tragedy and never leave their small children unattended in the tub.

"I don't want anyone to endure the pain that my entire family has," she said.

But she also wonders whether Dyllan's death could have been avoided. The state Department of Children and Families had previous involvement with the family, although the details of those cases were not available Wednesday evening.

Griffiths said the cases involved Roe's care of the boys, and she said DCF should have done more to follow through.

No charges have been filed against Roe. She told detectives that she turned down Michalski's advances on March 30, according to the report, because "she does not like to have sex while the kids are in the tub."

Griffiths said her daughter has gone through counseling to deal with Dyllan's death. And two months ago, she said, Roe and Michalski had their third son.

Camille C. Spencer can be reached at cspencer@sptimes.com or (813) 909-4609.